A commercial time-resolved fluorometer will be combined with a fluorescence microscope using both flash lamp and excimer laser (with dye laser attachment) excitation. Time-resolved microfluorometry is based on the work of Prof. S. M. Fernandez, the only previous investigator using this technique. Time resolved microphosphorometry will also be employed. This technique has not been reported previously, but is a straightforward extention of microfluorometry to a slower time scale. Laser spot excitation coupled with a computer controlled microscope stage with 0.5 micron precision gives excellent spatial resolution. Signal acquisition and digitization equipment used in the instrument is suitable for optical lifetimes ranging from 1 nanosecond to one millisecond. The major user group consists of 12 proposals with a total of 18 investigators. Twelve of the investigators are associated with the Medical College of Wisconsin in five different departments, five with other Milwaukee based research institutions, and one from Princeton. Nine of the proposals are associated with immunochemical, biochemical and biophysical events on membranes. Titles of these proposals are: (1) Time-Resolved Fluorescent Microscopic Study on the Topography of Immunoglobulin G Fc Receptors and Functions of Macrophages, (2) The Molecular Basis of Crystal-Induced Diseases, (3) The Measurement of Intermolecular Distances Between Flavoproteins and Heme Proteins on Endoplasmic Reticulum Membranes, (4) Spectroscopic Studies of tRNA, (5) Rotational Diffusion of Fibronectin by Fluorescence and PHosphorescence Anisotropy, (6) The Time-Resolved Fluorometric Study on Drug-Induced Immunohematologic Disorders, (7) Monooxygenase Induction in Fish, (8) Extracellular Spatial Gradient of Dissolved O2 DEtermined by Quenching of Xanthene Dye Triplet Emission, (9) Molecular Organization of Desmosomes in Cell Assembly, (10) Early Effects of Interferons on Cell Membranes, (11) Time-Resolved Fluorescence Study on the IgG Heterosaccharides: Fc:Fc Interaction in Immune Complexes (12) Diffusive Processes in Membranes: Fluorescent- Phosphorescent- and Spin-Probe Study.